Placed on the Dead Void altar to summon the final bossfight.
integrion_core_block is unbreakable, obsidian-tier hardness and blast resistance (-1.0F hardness, 3,600,000.0F resistance).
Placed on the altar in the Dead Void, surrounded by the correct redstone torch arrangement, it starts the Integrion Bossfight.
integrion_core_block